Elastic-fluid-pressure-actuated means for adjusting the proportional band of a controller



Dec. 11, 1956 w. E. BAUER 2,773,506

ELASTICFLUID PRESSUREACTUATED MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER Filed Dec. 28, 1950 8 Sheets-Sheet 1 WITNUAC I F I G. l

63 SET POINT J ALTERNATE CONNECTION sxu. 8| axn. Am. EXH. Am. zxn.

THROTTLING RANGE 86 RESET INVENTOR. WILLIAM E. BAUER IW/QM ATTOR-NEY.

Dec. 11, 1956 ELASTIC-FLUID-PRESSURE- Filed Dec. 28, 1950 FIG.2

W. E BAUER PROPORTIONAL BAND OF A CONTROLLER ACTUATED MEANS FOR ADJUSTING THE 8 Sheets-Sheet 2 INVENTOR. WILLIAM E. BAUER ATTQRN EY Dec. 11, 1956 w. E. BAUER 2,773,506

ELASTIC-FLUID-PRESSURE-ACTUATED MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER Filed Dec. 28, 1950 8 Sheets-Sheet 3 FIG.41

INVENTOR. WILLIAM E.BAUER ATTORNEY.

Dec. 11, 1956 w. E. BAUER 2,773,506

ELASTIC-FLUID-PRESS -ACTUATED MEANS FOR ADJUSTING THE PROPORTI L BAND OF A CONTROLLER Filed Dec. 28, 1950 8 Sheets-Sheet 4 INVENTOR. WILLIAM E. BAUER ATTORNEY.

Dec. 11, 1956 w. E. BAUER 2,

ELASTIC-FLUID-PRESSURE-ACTUATED MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER Filed Dec. 28, 1950 s Sheets-Sheet 5 el zlz INVENTOR. WILLIAM E. BAUER ATTORNEY.

Dec. 11, 1956 w. E. BAUER BLASTIC-FLUID-PRESSUR-E-ACTUATED MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER 8 Sheets-Sheet 6 Filed Dec. 28, 1950 INVENTOR.

WILLIAM E. BAUER ATTORNEY.

Dec. 11, 1956 w. E. BAUER 2,773,506

REI-ACTUATED ME ELASTIC-FLUID-PRESSU ANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER Filed Dec. 28, 1950 8 Sheets-Sheet 7 INVENTOR; WILLIAM E. BAUER ymj/m ATTORNEY.

W. E. BAU

Dec. 11, 1956 MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER ELASTIC-FLUID-PRESSURE-ACTUATED 8 Sheets-Sheet 8 Filed Dec. 28, 1950 FIG.38

FIG. 37

R E .U m A 7B A m E mM m L K W ATTORNEY.

,,. t s Pa eh Q 13 ELASTIC-FLUID-PRESSUREeACTUATED -MEANS FOR ADJUSTING THE PROPORTIONAL BAND OF A CONTROLLER William E. Bauer, Palmyra, N. J., assignor to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn.,.a corporation of Delaware Application December 28, 1950, Serial No. 203,151

4 Claims. (Cl. 137-86) This invention relates to fiuid-pressure-operated controllers adapted for either manual or automatic operation under the control of either a manually operable transmitting instrument or of an automatically operable measuring instrument, which instruments may be located adjacent thecontroller or remote therefrom.

It is an object of this invention to provide a controller which, because of its novel and simple construction, gives improved and accurate control action.

More specific objects of this invention are to provide a controller having one or more of the following novel features. The controller is responsive to one fluid pressure (herein called the measured variable pressure) which pressure is proportional to the measured variable and to another fluid pressure (herein called the set point pressure) which pressure is manually adjustable to vary the value of the controlled variable which,-at any instant, the automatic controller tends to maintain. A plate is adjustable to reverse the connections between the controller and the set point pressure and between the controller and the measured variable pressure was to reverse the directions in whichthese pressures actuate the controller.

The controller contains a control-exercising element, such as a flapper valve. Two springs bias this element in one direction or the other. handle varies the direction in which these springs bias the flapper. A normally stationary nozzle cooperates with this flapper and is manually adjustable.

to area differences." The use of two springs rallows this bias .to be applied to the diaphragm in either direction.

. ".The aforementioned set point .pressurejandfmeasnre'd variable pressure cooperate to produce (a third pressure (herein called th con'troller output pressure).

' The throttling range 'orproportional band'of the con.-

troller is manuallyv adjusted by fluid operatedmeans containing a .relay having a substantially one to-one ratio so that the controller operates in a sensitive and accurate manner at every position of adjustment ofpthe throttling range orproportional band.

A .fourth. fluid pressure (herein called the The controller has improved means :foradjusting, the

' proportional hand. These means includea. fluid-operated A' manually operable This adjustment of the nozzle permits establishing normal-or ati rest position of thediaphragms so that two of these diaphragrns have equal effective areas. The spring ad-f" "justm'ent introduces a compensating forceto cancel out force. differences invthe remainingset of .diaphragms due 2,773,506 Patented Dec. 11, 1956 motor governing the control-exercising element and a 'fluid conducting-network between the controlled pressure of said controller and said motor. Said network includes a manually adjustable restriction designed to operate in the laminar or viscous flow range connected in series with a non-adjustable restriction so designed that in the range of operation of the controller, the flow through said second restriction will change from a lam inar to turbulent nature. The pressures in this network are applied to said motor in such a way as to provide adjustment of the throttling range by means of the manually adjustable restriction. This transition from laminar to turbulent flow in said non-adjustable restriction causes an automatic. increase in its resistance to flow as the deviation from the set point increases in either direction.

. This automatic increase in resistance narrows the prophragms AA--LL.

Drawings Fig. 1--schematic diagram with parts in longitudinal cross section- Fig.-2--front elevation with parts broken away in longitudinal cross section, showing the controller formed of a number of parts A, B, C, D, E, F, G, H, I, J, K, L, M, and N. i

Figs. ,3-end view as viewed fromthe left of Fig. 2.

Fig. 4--longitudinal cross section taken from Fig. 3 .on line 4-4 showing the chambers 116 and the dia- -i Fig. 5end view of ring A.

Fig. 6end view of ring B. Fig. 7end ,view of ring C. Fig. 8--longitudinal cross section from Fig.-7 on line Fig. 9--end view of ring D. Fig. l0-longitudinal cross section from Fig. 9 on line Fig. 11-endview of ring E.

- 'Fig. 12--longitudinal cross section from Fig. 11 on line 12-12.

. r Fig. l3longitudinal cross section from Fig. 11 on line 1313.

' Fig. 141ongitudinal cross section from Fig. 11 on line 14-14.

Fig. Ii -longitudinal cross section on an enlarged scale of resistance screw 24.

Fig. l6'-end view of ring F. Fig. 17 longitudinal cross section from Fig. 16 'on line 7 7- 1 Fig. l8 -end view of ring G.

Fig. 19-end view of ring H.

Fig. 20-longitudinal cross section from Fig. 19 on line Fig; 21-end view of ring I. 4

Fig. 22--longitudinal cross section from Fig. line 22-22 on an enlarged scale. 7

Fig.- 23.longitudinal cross section from Fig. 21' on line 23 -23.

' Fig. 24--perspective view of spring 30.

Fig. 25-face or plan view of pneumatic switch 73.

--Fig.' 26end view of ring J. Y

Fig. 27-longitudinal cross section from Fig. 26 on line 27-27.

" Fig. 28-,end view of ring K.

' 1 Fig. 29--end view of ring L.

I Fig. 30longitudinal cross section from Fig. 29 on line 30-40. 1 e .Fig. 31-longitudinal cross section from Fig. 29 on line 31-31.

General description Fig Lshows that the device ofthis invention =is-acontroller adapted to'beactuated'by-a'-fluid, usually-air. A filtered '-air supply (hereinafter :and in the drawings FAS) is. connected through conduit 20- to chamber :16. An. inlet .valve 21 controls the 'supply of: air -from -cham -ber '16 to-the valve. chamber 15. An exhaust-valve 122 cooperates with the tinnerenduof inlet valve 2l:.to:--permit the. exhaust. of air 1' from :charnbera 15 1o chamber:14 and port 23 to atmosphere. a'GhamberZ16 sis alsoconnected through a fixedrestriction 24 to motor chamber 13, and, through nozzle generally indicated at 25, to valve :chamber :which is exhausted to atmosphere through port 26. Pivotally mounted in chamber-10 is-aqvalve, generally indicated at'27,:-adapted to: cooperatewith the inwardly projecting end. of nozzle- 25cc as -to-. vary the :fiow .of fluidntherethrough. .A valve-actuating mernber,

generally indicated at 28, contacts valve 27 so as to -acmate it. Aconical: spring 29 stresses-member 28 .in one .direction and arurshaped spring 30 Fig. 24) stresses 7 it in the. opposite direction.

A :manually operable t member 30B varies the bias of spring 30 on-member 28 'so that the bias of spring 3tlum-ay bemore than-or'less than the bias of spring 29. In other words, member 28 may be biased to the right or tothe-left as seen in Fig. 1.

The controller is arrangedto be responsive-to a measuring instrument, disclosed as a flow meter 32 responsive to the flow of fiuid through a.conduit 33. Of course, any type. of measure. instrument which :isc-apable of converting a measured variable into an air pressure may be employed. The controller::controls the actuation .of I final v:controlrvalve '34 in. conduitk33 ornis otherwise arranged to vary a quantity or condition so as to affect the @value .Ofi the controlled variable of the .process under control. Flow meter 32 has a diaphragm 35 which rocks a ;.flapper,lever 36;about;a;supporting,. sealing bellows-37 so that the flapper lever 36 varies the flow of fluidffrom a ;;noz;zle.- 38rsupplied'with air ,from a source39; through a restriction 40. The variations caused tby the variations in flow through nozzle 38 -are applied .-to.a follow-up ;.be1lows 41:. soas to;restore.theflapperlever;36-to its original position. Air pressure proportional to the yalue of the variable measuredby the measuring instrumeritSZ is4fed through pipe 42 to an i nlet port 43 and. to a gauge 'A remotely located, manually operable, fluid pressure transmitting instrument is contained within the ca'sing indicated by the broken lines 45. This-transmitter con- --sists of a supplyofair 46-whiclr transmits air-through a restriction 47 to a nozzlea48 and a motor--bellows 49 .uhaving; a free endzsecured to-a 'F-shapechexhanst.-.port

,.59..leading. to. a follow-up bellows 60 having a -mechanical connection 61 forming another input to differential .57 so as torestore flapper 55 to its original position. I

Pipe58 also has a branch 62 which 'leadsio a/second aep'rasoe inlet port 63. Pipe 58 has a third branch 64 which leads -through oneset of ports 65-of-a valve which ismanually operable by handle 66. The opposite side of valve 65 is connected to a branched pipe 67 containing gauge 68 and terminating in the controller in chamber 3.

Another source of fiuid pressure 69 communicates with a second valve section 70 having an outlet port connected to a-pipe 71 which terminates in the controller at chamber-1 A-second output port of valve 70 connects to 10 an exhaust port 72. The ports of valve section-65 are arranged so that communication is established between ;pipes, 64;an d 67-whe nvalvesection 70 isset to establish communication between pipe 71 and exhaust i72- sothat there. is no pressurein chamber 1 and the valve in controller chamber 3 is in the left hand or Manual position. When the ports ofivalv esection 70lare set by handle 66 to establish communication between supply 69 and con duit 71 so that supply pressure is supplied to control chamber '1, the valve in chamber 3 is in the right-hand or-Automatic position while theair pressure under-the control of manually operable handle 56 is shut off by the valve section 65.

Figs. 21.1and 25.-show that ports 43 and 63 terminate beneath a plate.73 which may be connected to the constroller casingin either of two positions. In the position .shown.in-.fulllinesqin Fig.1, plate 73 contains conduit 74 connecting port.43 with chamber 11 while conduit *75'connects port63 with chamber 9. In such a position -chambers11 is :thus subject to the air pressure which is proportional to the variable measured by the measuring element i32iwhile chamber-9 issubjected to the pressure which;is proportionahto the pressure which is manually .testablished' by handle 56 which thus sets the point from .-.which.-the deviations-of the measured variable are measured. :Anmorecomplete description of the actual con- :structionof theseports and; conduits is given below.

. Conduit 76connects chamber 16 with chamber '7 and .8- throughrestrict-ion 77 and connects chamber 16 .with ,chamher;,5.through restriction 78. Chambers 5. and 6 .,arezconneptcd;by a conduit containing restriction l9.

[Ifhe regulated fluid pressure established in chamber .15 by the operation of the controller passes through conduit 2 80 and -manua1ly adjustable restriction 81 to. chamber This -air alsopasses through conduits 80, 82, chamlib r$:2;and1 3,and conduit 87m chamber 4. Qharnber- ;3;;is connected by conduit 83 to the, final eon trol -valye '34. Conduit 111 containing .a manually ;operable restriction 86 connects conduit 83 to chamber 1. i :raralls wi i' n i Operatiomof controller i h w the v bl fl d pte u ein e po repnnss nthmus condu 7 o s mbc f tan t east-pain flu dr ess e nl t por n st dthr ie conduit; 5; l chamberjii. Al soinfig. '1, valve 89 in tabs-s im. lsfifisilfll tdt e nfihe hkhand r.. Automac m .snth mea re vari le l w- 1 ...3 ari s..dianhtaemflisau ss pp lever to lva rtt e r s lcs ap n t ro 92 1 'This .yari tbninlheflu pr ssu e f om, Source P p ,,cau'sesbel1ows 41 to give .a follow-up movement to flapper, lever 36 and thus restore it to its original posim 1s. Ihis variation in-fluid pressure is also transmitted through p p 2, ulfi lpqr zfil an co du 74,10 sha ..hcr 141 t itsm sou c p ui pr s P3 5 :u li h z'eoa ro otmenua sn l i hand 56 t 11pes58 6 inlet port '63, and conduit 75 to chamber 9. 'QIhere isthus established in chamber 9 a fluid pressure which;,actuates the valve-actuating member 28 in .the opposite ;directipnto the pressure in chamber '11. ydifierencein the pressure in chamber 11 from; that n chamber v9 ca1 1ses rod- 28 to move flapper 27 with spectto nozz le;25. "This varies the pressure in chambers25Aand 13 andcauses inlet valve- 21 or exhaust valve 22 to be opened so as to admit air to or exhaust fi pir frorngchamber '15, which "therefore contains an air s asm pressure regulated by the controller. This air pressure from chamber 15 is transmitted through conduits 80 and 90 to chamber 12.where it causes a follow-up move ment of rod 28 and flapper 27. This variation in pressure is'also transmitted from chamber 16 through conduit 80 and variable restriction 81'to' chamber 6 where it varies the pressure applied to diaphragm DD and thus varies the pressure in chamber8 and gives a throttling range adjustment to rod 28, and consequently to flapper '27. This variation inpressure in chamber 15 also passes through conduits 80,82, and chambers 2 and 3. Since valve 89 closesconduit 87 this pressure chamber passes through conduits 83 and 111 and adjustable restriction v.86 to chamber 4. A variation in pressure in chamber 4 moves diaphragm CC and thereby varies the pressure applied from chamber 5 through restriction 79 to chamber 6 which in turn influences the pressure in chamber 8 and actuates rod 28 and consequentlyv flapper 27 with a reset action.

vIf ,it is desired to actuate the controller and consequently the finalcontrol valve 34 manually instead of automatically by means of'measuring element 32, handle 66 is shifted sothat communication is shutoff by valve section 70 between source 69 and conduit 71 to chamber 1. Communication is opened from chamber 1 through conduit 71, valve section 70, and .port 72 to exhaust. This reduces the pressure in chamber 1 and causes valve 89 to shift because of its bias (not shown) from the right-hand or Automatic position of Fig. l to the lefthand or Manual position. With valve 89 in the left-hand 'or Manual position, adjustment of handle 56 varies the air pressure put out from relay casing 52 through conduits 58, 64, valve section 65, conduit 67, chamber 3, and a conduit 83, to final control valve 84. This air pressure is also applied from chamber 3 through conduit 87 to chamber 4 where it serves to adjust the instantaneous position of flapper 27 so that it is in proper proportion to the setting of the final control valve 34.

Detailed description of controller Referring to Figs. 2, 3, and 4, it will be seen that this 7 controller is composed of a plurality of parts, of generallydisc or cylindrical shape, and numbered respectively A, B, C, D, E, F, G, H, I, J, K, L, M, and N. The parts -A Nv are separated by the diaphragms AA, BB, CC, DD, 15.13,,FF,=GG, HH, ,II, J], KK, and LL. Parts C and D are sealed by a gasket 91A (Fig. 4). .The'parts A'-N are secured together by a plurality of bolts 91 which are attached by means of screw threads 92 to part N and which are held in position at their outer ends by nuts 93. I; The controller may beheld at any convenient position Qbya mounting plate 94 secured to the' controller. by

screws 95 (Fig. 3). j

. Pressureregulrrting pilot valve or relay Figs. 1, 4, 35, and 36 show that a supply of filtered I air is connected through pipe 20 to chamber 16 with 1 which conduit 80 communicates (Fig. 35). Conduit 76 ,also communicates with chamber 16 by means of a'filter ,96; so that the supply of air from chamber 16. to restrictions 24, 77, and 78, and-to nozzle25, is filtered.

.Fig. 4 shows that part N also contains chamber to which air is admitted from chamber 16 through inlet valve 21 which is stressed towards the left by spring 97. Diaphragm LL separates chamber 15 from chamber 14. Spring 9 8 stresses outlet valve 22 tothe left as seen in Figs. 1 and 4. Outlet valve 22 is supported on diaphragms KK and LL and contains a T-shaped exhaust port 99 init.

Sheet 7, Fig. 33, shows the exhaust port 23 from chamber 14 to the atmosphere.

s-1,4, and 29-32 (Sheet 7 ShOW that chi es '13 formed. between part L and diaphragm Figs. 36,

to chamber Figs. land 32 showth at communication is established between chamber 13 and conduit 76'by means of restriction 24. I I Restrictions 24, 77, and 78 threaded hole in it. Into this hole fit screw threads 97 on the outer tubular body of restriction 24, which has a tubular portion 98 of reduced size and an inner cavity or counterbore 99' into which is fitted a tube 100 of small cross sectionwhich forms the restriction proper. The outer end of this hole or bore beyond conduit 76 is closed by a screw-threaded plug 101.

Figs. 29, 28, 26, and 22 show that conduit 76A continues to the left from chamber 13 through part L, .diaphragm JJ, part K, diaphragm II, part J, chamber 11, conduit 76A, diaphragm HH, and part I to nozzle cham ber 25A in part I (Fig. 22). v

Fig. 22 shows nozzle chamber 25A extending radially of-part I at the end of conduit 76A. The nozzle, generally indicated at 25, consists of an inner tubular member 25B having flanges adjacent its upper or outer end to receive a sealing ring 25C. The inner endof nozzle 25 which projects into chamber 10 has an inner bore of small area 0 through it. The outer end of chamber 25A is sealed with member 28 as will be more fully described hereinafter.

Returning to Figs. l-4, 32,29, 28, 26, 21, l9, l8, l7, 16, '11, and 12 show that conduit 76 passes from chamber 16 to chambers 7 and 8 (through restriction 77) and to chamber 5 through restriction 78.

Restrictions 77 and 78 may be identical with restriction 24' (shown in Fig. 15) and are located in radially extending cavities in parts E and F respectively. -The 3 2,; and.29 show that conduit 76 passes fromchamber,

1 6 through holes (not shown) in diaphragms KK and'LL outer ends of these cavities are closed by screw threaded plugs 77A and 78A.

- Figs. 1, 4, 34, 35, 33, and 29, show that chamber 15 is connected to chamber 12 by conduits 80 and 90. Figs. 29 and 31, 28, 26, 2'1, 23, 19, 18, 16, 11,14, 7, and 8 show that chamber 15 is connected bymeans of conduits 80 and 82 with chamber 2.

Variable restrictions 81 and 86 v Fig. 14 shows that at the junction of conduits 80 and 82 there is an adjustable restriction, generallyindicated at 81, which controls the passages 102' and 103, to chamber 6.. Restriction 81 is the throttling range restriction. Figs. 11 and 14 show that it is located in a radially extending cavity at the end of 102. An' indicator 104 is mounted on the outside surface of part .B adjacent an operating handle 105. Conduit 102 is sealed from conduit 103 by a needle plug 106 having a perforation through itin which is mounted a needle valve 107 secured at one end of a needle valve screw 108 which is fastened to handle so that rotation of handle 105 adjusts the amount of opening between needle 107 and the adjacent cylindrical opening. in needle plug 106.

Parts E and F, chambers 6and 7, and diaphragm DD form a one-to-one relay. Fig. 17 shows that chambers 7 and 8 are in open communication through an unrestricted conduit 109 which communicates with the opposite side of restriction 77 from that connected to conduit 76. Figs. 1 and 13 show that chambers Sand 6 are connected by a conduit 110 in which is located restriction 79 which may be identical with restriction 24 (Fig. '15). Figs. 9, 10, 7, and 8 show that chamber 3 (which comand 37 show that conduit62=r with chamber 9 (Figs. 19 and '20). showthat plate 73 is adapted to be secured against the outer surface of part I which is shown in Fig.-,37, by means of a flat cover 130 and screws 131. Plate 73 has .imu isatr w t pin L83) ;;is connected w th rhamher i cylindrical instead of being conical as is thegneedle r107 of restriction 81. Restrictionfio is the t-gadjustment. ispar B which 1 8. errl e hte megseal l cavity 1 12 it open to atmosphere throughexhausQEQfl Fig. shows part A having i motor ca ty lgiri it to wwhich air is adapted to be suppliedgfrom pipeflht sis seen inFigs. 7, 4, and 5, .which show that pipe fll fits intoa radially extending cavity 114 part C whichcommunicates with a transverselyex nd ng cavity 1 ;com-

rnunicating with. a hole 116 in', -d; aph1 agnrB B,-a holeill7 shape ho1e119 in part A communicates with chamber 1 ther n Switch plate for change front direct to reuerse ac tion .E 1,: and 371hQWh .12 i ,Eigs.;21

tes Lin inletport 63 with; a 1:12. 1 121 tin ,which communicates by cond t;

- t he;.outer surface of part I. ,-,$imilarly,,conduit;42nterminates in inlet port 43 whi hicomntunicates byt meanscf conduit 74 with port 123 in the outer surfacemflpartl Part I also has two cavities 124 and 125 extending ininwardly extending portion .127 which communicates with chamber 11. P011125 likewise has at its inner end a transvcrsely extending porti128 which extendsthrough an op ening in; gasket 16G to; port :128 ,in ;-parts 'HnWhich communicates through .a r radially extending port 129 Figs. 21 and ran irregularly-shaped perforation 13 1 adapted to overlie port 121. Perforation 131 communicates with perforation 134 which overlies port 124 so that port 131 is connected to port 134 and consequentlyset point pressure 4 :port 63 is connected with chamber-'9. Plate .73 also has direct toreverse operationthat is it is possibleto change the operation of a controllerfrom one in which the output pressure ,varies in the same direction as the input pressure to one in which the output pressure varies in the reverse direction to the input pressure. This switch from direct to reverse operation is accomplished by rotating plate 73 onehundred and eighty degrees from the position in which it is shown in Fig. 25. In this reverse I position, perforation 133. overlies perforation 121 and perforation 135A overlies perforation so that set point pressureinletport 63 is connected to,gzhatr b er' 11. In this reverse position, perforation131 overlies perforation 123 and perforation'134A overlies port 124. Thus, ,the variable. pressure inlet port 43 is connected to chamber 9.

perforations 131, 133, 13 L135, 134A, and A, sim- I ple holes v and byforming the inner face of the cover 30 .withuC lirl lgations of the shape shown in Eig.:25. This modification operates in exactly the same manner described;

Plate 73 and cover 130 may be modifiedby making the Xalv act ating a t28au spli r gs iastappliedthereta Figs. Khalid-2.4. show-v that. the rmember,.sgencrallymindi- -cated rat 28,-which.;actuates.the Iflapper :generally indicated:at;27, is supported in chambers; 8,5T9,:10,r 11,.:and

a1'2iby meansof; gaskets EEFF, GG I-IH, ILandIJJ.

:Member 128.:c0nsists essentially of. a :bolt,.140 :having a head 1.41: and atiscrew threaded end :142 to iwhichra ;nut143 is secured. :Thecentral portionofvbolt;;has :awtube 144 .rslid over. it. Tube 144 :is provided withza boss having aflat, radially-extending face'145- which engages with the short legt27F' of :valve :27 ;(Fig.r,22). iPig. 23 shows a I generally conical, :helical spring.;29 u'WhiChc stresses memberZS .to. the leftyas shown .inxth vdrawings A, generally .U.-shaped spring Gil-engages face 1450)? boss c144 and stresses member :28 to the-right. The lower bight of spring. 30 is engaged by the conical -6l'1d'i39A of a screw 30B which is adjustable: .and :which is secured inadjustedposition by-means of alocknut 30C. Screw 30B extends through a plate 30D aformingwone .wall' of rcham'ber l-tluand part]. A .cap "30E veryisimilar .tothe valve :stem cap of ;an automobile :tire encloses the'outer :end of stem B. Since the outer wall-of part I :is cylindricalwhile plate 30D .is flat therelis a leak around the edge ofiplate '30Duwhichprovidcssthevex- 'haust 26 totatmosphere from chamber 10.

:By adjustment of .screw 30B, the .1 bias which :spring 30 iexertscitouthe right of memberr2$ maybe adjusted -;to be moreori-less than-the bias rwhichspringi29 exerts atoathelleft. Thus,:the position of-balance or -rest,= which theMaIVe-actuating member 28 and its associated-parts rtendato assumezwhen the pressures applied toait areequal, maybeiadjusted .bY1SC1'CW'3GB.

cans to n z aintain diaphragm areas substantially. constant 'Figs. "1, 4,18, and'28 show that diaphragm EE, part G anddiaphragmFI- define a chamber Whichis vented toatmosphere through a port 151 and that diaphragm, 11, part K, a -diaphragmIJ define a chamber which is vented to atmospherethrough. a, port 161. In chamber 150 between the valve-actuating member 28 and dia- ;phragms'-EE-and'-FF are'reeriforcement-plates 152 and 1153. :In chamber 160 between valve-actuating-mcmber 28 and diaphra-gms II and "II are reenforcement plates 162 "and 163. 'These plates =aid in preventing the 'dia- -phra-gms fromdistorting despite the differences {in pressures appliedtothe-opposite sides thereof-and therefore aid in maintainin g theaccuracy of the controller.

flfhrott ling mnge:0r;prop0rtional band adjustment ,fl' he throttling range restriction .81 and the cooperating fixed-restriction 79 are designed toproducena narrowing of the proportional band or throttlingrange, as the deviation from the control point increases in either direction. This action is desirable .sincemitmaterially improves the speed of controller response without causing instability or "hunting.

For very'small difierences in pressure between a point inconduit 80and a-point in-chamber 5, the action of the restrictions 79-and 81 is to cause the controller-to "operato at a proportional band expressible bythe following mathematical relationship:

Proportional band'equals fixed band-multiplied by Kat Rani-.1379

where thejfixedband isva constant determined by othcr components of the controller and the expressions Rarand R79 are the resistances to air flow of the restrictions 81 and 79, respectively.

From this expression it can be seen that, if R81 is increasechthe proportional ,band is-vwidened, and, if, R31 is decreased, the band is made narrower. Conversely, ;.if

, R19 is i i cts qsed, the band narrows, and, if Rois qdccreased, the,band vwidens. Restriction 81 is a manually 2, its, so 6 adjustable restriction'for setting the desired proportional handy I e I Fixed restriction 79 is a capillary tubesimilar to the .,fixed restriction 24 (Fig. 15) soproportioned that, as the difierence between the pressures at 80 and increases (i. e., controller departs from control point), the flow through the fixed restriction '79 changes from a laminar or viscous nature to aturbulent nature. It can be shown mathematically and experimentally; that this transition from laminar to turbulent flow results in an increase in the resistanceof R79, thus narrowing, the proportional 1 band while the deviation from the set point isilarge. As

the controller returns the process variable to the set point,

the difference between the pressures at 80 and Sis reduced 81 with a conical needle valve 107 (Fig. 14) the air flow through restriction 81 can 'be made to stay within-the laminar or viscous range for a large percentage .of the values Ofl flow encountered within the range of controller Thus, the undesirable eifect'of having the operation. flow through the. restriction 81 become turbulent and cause a widening of a proportional band is prevented.

An additional. feature of thisnarrowing of the proportional band, as the deviation increases numerically is that it ofisets an undesirable widening of the band which results. when the pressure in conduit '80- drops ibelowthe pressure in chamber 5, this widening being caused by the compressabilityofair. M

Modified form of proportional band adjustment Fig. 38 shows a modified form of proportional band adjustment which may be substituted for restriction 81 (shown in F1g.*14) in thepneiimatic circuit shown in This adjustment contains a restriction generally indicated .at 81A corresponding to the restriction 81' (Fig. 1). In'this modification, the needle valve 207 is frusto-conical in shape instead of the conical shape needle valve 107 (Fig. 14). This needle valve 207 cooperates witha cylindrical opening 208 in the needle plug 206.

One specific example of the size of the restrictions 79 and 81A which has been found in practice to operate as described above is as follows: Restriction 79 (Fig. 15) has a tube 100 which is /8 of an inch in length and 0.0085 of an inch in internal diameter. Restriction 81A (Fig. 38) has a cylindrical perforation 208 in needle plug 206. This restriction is of an inch in length and 0.0625 of an inch in internal diameter. Needle valve 207 tapers 2 degrees and 22 minutes and has its smallest diameter less than that of perforation 208 and its largest diameter larger than the diameter of perforation 208. When needle valve 207 is projected to its full extent into perforation 208 so that the wall of the needle valve 207 lies against the rim of the perforation 208, needle valve 207 projects into perforation 208 to a distance of 0.121 of an inch.

One-to-one relay The pressure divider circuit used for the proportional band adjustment causes a time lag in the overall resistance of the controller. This time lag is a critical function of the volume into which the positive feedback pressure is fed (i. e. chamber 8).

The inclusion of a pneumatic relay between the output chamber 6 of the throttling range adjustment circuit and the positive feedback chamber 8 of the controller pcrmits a considerable reduction in the effective volume included in the positive feedback circuit as compared to that which could otherwise be obtained practically. This relay may have a one-to-one or other suitable ratio. The response in controller output pressure to sudden changes in deviation between the process variable and the set point pressure is thereby improved considerably.

1 For this purpose, a one-to-one relay is 'employedcotn prising a motor or driving chamber 6 to which the throttling range adjustment pressure is applied through conduit 102 and variable restriction 81 and to'whichthe reset pressure is applied through conduit 110 andfixed restriction 79. Chamber 6 governs the pressure in chamber 7 to which airis fed from supply 20, conduit 76, restriction 77, a'conduit 109 and which has an outlet 212 therefrom controlled by the diaphragm DD. The output of chamber 7 is fed through conduit 109 to the positive feedback chamber 8. Restriction 77 acts as a theoretically inexhaustable source of fluid pressure at the maximum pressure used by-the controller. Exhaust port 212 is sufliciently large to rapidly empty chambers 7 and 8 to the lowest pressure employed by the controller, which is three pounds, approximately, above atmospheric pressure. Therefore, the pressure within the chambers 7,109, and 8 can be changed as rapidly as dictated by the changes in the measured variable regardless of the capacity of these chambers. ,1,

While, in accordance with the provisions of the statutes, I have illustrated and described the best formof the invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of the'invention as set forth in the appended claims, and'thatin some cases certain features of the invention may sometimesbe used to advantage without a corresponding use of other features. I

Having now describedymy invention what I claim as new and desire to secure by Letters Patent is as follows: 1.1'Fluid-operated means for adjusting the proportional band of a controller, including, a fluid-operated motor,

mechanism exercising the control action of said controller under the control of said motor in response to the variations in the measured variable, a pressure-reducing fluidv conducting network, a source of fluid pressure connected to said network to furnish a pressure variablein proportion to thevariations. in the measured variable and under the control of said motor and said mechanism, a manually adjustable restriction connected in said network and located between said source and said motor and comprising a stationary cylindrical conduit of the order of 0.0625 inch in internal diameter and a frusto-conical needle having its minimum diameter smaller and its maximum diameter larger than the internal diameter of said conduit and movable axially of said conduit, the angle of taper of said needle being of the order of 2 degrees and 22 minutes, the resistance of this restriction to fluid flow being substantially independent of the flow through it, a reference source of fluid pressure connected to said network, and a second restriction connected in said network and located between said reference source of pressure and said motor and comprising a fixed capillary tube of the order of 0.0085 inc-h inside diameter and inch in length, the pressure drop across said second restriction varying as a non-linear function of the flow through said second restriction because of the tendency of the restriction to change the flow from laminar to turbulent.

2. A pneumatic proportional band adjustment for an air-operated controller having a fluid output pressure varying in response to variations in the measured variable governing said controller comprising, an air-conducting conduit connected between the output of said controller and atmosphere and including a manually variable restriction of generally frusto-conical shape and operable within the laminar state of flow of fluid therethrough over a large portion of the range of output pressure, a substantially cylindrical capillary tube having a ratio of internal diameter to length of less than one to seventy-five and in said conduit operable to change the state of fluid flow therethrough from a laminar to a non-laminar flow as the control-exercising mechanism of said controller deviates from the preselected value of the measured variable which the controller is set to maintain, and an air-oper- 11 ated m 0,tr connected under the control of the pressure of the air insaid conduit between said restrictions, said ,motor'forming part ofthev control-.exercising'means ,of

j said controller.

3. Fluid-operated means for adjusting the proportional band' of a controller whose output is a fluidpressure; said means including, a fluid-operated'motor responsive tosaid ,output 'fluid pressure which varies as the measured variable; governing the process under controL-a first conduit connected to said motor'to supply said 'fluid-pressurepro- ,portional" to the changesin said measured variable, a first ,TCStI'iCfiOIliH"Saldfi1St ;conduit manually adjustable to vary the *fiow through said conduit and maintaining the flow of fluid through said conduit laminar'and the resist- 'ance to fthe=flow of fluid substantially constant throughfluid; pressure-adapted to serve as a reference, a second conduit connected to said motor-and to said supply'of --referencefluid pressure, a second'restriction comprising a 'fixed" capillary tube' of the order of 0.0085 of an inch inside diameter and A; of an inch in length in said second conduit changing the flow of'fluid through said second the proportional band of a controller, including, a motor having a plurality of chambers each responsive to the pressure of an elastic fluid,a flapper and nozzle one moved relativeto member in response to the resultant ofthe pressures in said motor chambers,-said flapper-and nozzle cooperating to control the output pressure of the controller, a first elastic-fiuid-pressure-transmitting connection conducting changes in said output pressure. to atmos- "phere,-amanually adjustable-restriction in"said -first-connection having a resistance to fluid flow substantially in- "dependent of the flow through it, a first chamber which is the governing chamber of -a relay and whichis-connected' -in-said first connection to the 'output sideof'said first-restriction, a secondrestriction connected in said firstconnection between said first chamber andiatmos- *phereandhaving a'resistance whichvaries-as a non-linear "function of'theflowthrou'ghit because of the tendency of'said second restriction to 'change the flowthrough it from laminar to turbulent, a second elastic-fluid-pressuretransmitting connection providing an=ample-supply of=fluid to one of the-said chambers of said motor under the control-'-of=-said relay, -a'fixed -restriction connected on its -inletside-to :a supply of elastic fluid under-pressureysaid one of the said 'chambers of said motorconnected to the outlet side of said fixed restriction and in said-second connection, a :second chamber' which is the :governed xchamber :of said relay and which 'is connected in "said second. connection tothe :output side of-said fixed re- ".striction and: to said one :of the chambers of ssai'dymotor,

. andnaivalve insaid second chamber operable in response :to :any change in the pressure .in either said first-:or :said second-chamber of said relay'andicontrollingthe outlet between-said second connection andzatmosphere.

References Cited in' the file of this patent UNIT-ED STATES ,PATENTS 12,141,082 :Dickey Dec. 20,'1938 2", 431,210 Tamm= et.-al. "Nov. 18,:1947 2,481,395 Carns $Sept. =6, 1949 2,517,051 Swenson Aug. 1, 1950 2,518,244 Moore Aug. 8, 1950 2,638,911 'Griswold'et a1 May 19, 1953 OTHER REFERENGES Moore Products (30., Philadelphia, Pa., .Nullmatic Controller"instructions 505$,i1948, pp. 2-7, 11,23. 

